1. Field of the Invention
The present invention relates to a camera having a lens barrel and a camera body, wherein at least one of the lens barrel and the camera body include an actuator, and, more particularly, to a camera system having an actuator, such as an ultrasonic motor, which reduces or eliminates the influence of vibration generated when the actuator is driven.
2. Description of the Related Art
Camera systems are known which include actuators, such as ultrasonic motors and DC motors. The actuator may be positioned inside a lens barrel and used as a drive source for driving lenses necessary for a focusing operation, such as a zoom operation. Further, the actuator may be positioned in the camera body and used for film feed or as a drive source to drive, e.g., a mirror.
However, in the conventional type of camera system which uses actuators, vibration caused by an actuator's drive operation, which occurs in the actuator or in a member driven by the actuator, may be transmitted to other components of the camera system. For example, when the actuator is an ultrasonic motor, vibration may be transmitted to component members of the camera system which are excited by the ultrasonic wave vibrations produced by the ultrasonic motor and which are located at positions in the vicinity of the ultrasonic motor. Further, vibration may be transmitted to component members of the camera system which are mechanically connected to the ultrasonic motor. Furthermore, overlapping of the characteristic (natural) frequency of the component members of the camera system and the frequency band of the ultrasonic wave vibrations produced by the ultrasonic motor may cause abnormal noise to be generated and abnormalities to develop in camera function.
Further, in a camera system having an ultrasonic motor and including a vibration detection sensor to detect vibration, the vibration detection sensor may detect abnormal vibration because of the vibration generated in conjunction with the ultrasonic motor drive. As a result, the vibration detection accuracy may drop. Specifically, the vibration detection accuracy may drop because the frequency band of the ultrasonic wave vibration produced by the ultrasonic motor and the vibration frequency band at which the vibration detection sensor itself vibrates are extremely close at approximately 20.about.30 kHz. Of course, it is possible to shift the drive frequency band of the ultrasonic motor or the frequency band of the vibration detection sensor by changing the type of ultrasonic motor or vibration detection sensor used. However, it is difficult to completely keep the drive frequency band of the motor and the frequency band of the vibration detection sensor from overlapping.